Enhanced Spin Conductance of a Thin-Film Insulating Antiferromagnet

Bender, Scott; Skarsvåg, Hans Langva; Brataas, Arne; Duine, RA Rembert

doi:10.1103/physrevlett.119.056804

Cited by 52 publications

(70 citation statements)

References 32 publications

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“…This limit implies a diffusive regime where magnons are in a local equilibrium described by a local temperature arXiv:1909.05881v1 [cond-mat.mes-hall] 12 Sep 2019 and chemical potential. This is in contrast to our earlier, stochastic treatment of thin-films (d l) where spin waves do not establish a local equilibrium [18]. Specifically, we study the spin transport by evaluating, via a phenomenological theory, the structural spin Seebeck coefficient S and magnon conductance G. Furthermore, we investigate their temperature-and magnetic-field dependence by computing the interfacial conductance coefficients in a microscopic model for the NM|AF interface and evaluating the various coefficients using a Boltzmann approach.…”

Section: Introductioncontrasting

confidence: 98%

“…We find that the effects of inter-magnon scattering, which lock the two magnon bands together, is negligible. Furthermore, we show that even as the bulk spin resistivity vanishes near the spin flop transition, normal metal-magnet interface spin impedance ultimately bottleneck transport, irrespective of interactions, in contrast to the stochastic theory of [18] for thin films.…”

Section: Conclusion and Discussionmentioning

confidence: 73%

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Spin transport in thick insulating antiferromagnetic films

et al. 2020

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Spin transport of magnonic excitations in uniaxial insulating antiferromagnets (AFs) is investigated. In linear response to spin biasing and a temperature gradient, the spin transport properties of normal-metal-insulating antiferromagnet-normal-metal heterostructures are calculated. We focus on the thick-film regime, where the AF is thicker than the magnon equilibration length. This regime allows the use of a drift-diffusion approach, which is opposed to the thin-film limit considered by Bender et al. 2017, where a stochastic approach is justified. We obtain the temperature-and thickness-dependence of the structural spin Seebeck coefficient S and magnon conductance G. In their evaluation we incorporate effects from field-and temperature-dependent spin conserving intermagnon scattering processes. Furthermore, the interfacial spin transport is studied by evaluating the contact magnon conductances in a microscopic model that accounts for the sub-lattice symmetry breaking at the interface. We find that while inter-magnon scattering does slightly suppress the spin Seebeck effect, transport is generally unaffected, with the relevant spin decay length being determined by non-magnon-conserving processes such as Gilbert damping. In addition, we find that while the structural spin conductance may be enhanced near the spin flip transition, it does not diverge due to spin impedance at the normal metal-magnet interfaces.

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Section: Introductioncontrasting

confidence: 98%

Section: Conclusion and Discussionmentioning

confidence: 73%

Spin transport in thick insulating antiferromagnetic films

et al. 2020

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“…In addition to the bulk asymmetry, stemming from inequivalent sublattices, we find a crucial role for the interfacial coupling asymmetry (Fig. 2), consistent with the existing experiments [16,20] and theoretical proposals [25]. Such an asymmetry may occur even in a perfect crystalline interface [ Fig.…”

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Spin Pumping and Shot Noise in Ferrimagnets: Bridging Ferro- and Antiferromagnets

Kamra

Belzig

2017

Phys. Rev. Lett.

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A combination of novel technological and fundamental physics prospects has sparked a huge interest in pure spin transport in magnets, starting with ferromagnets and spreading to antiferro-and ferrimagnets. We present a theoretical study of spin transport across a ferrimagnet|non-magnetic conductor interface, when a magnetic eigenmode is driven into a coherent state. The obtained spin current expression includes intra-as well as cross-sublattice terms, both of which are essential for a quantitative understanding of spin-pumping. The dc current is found to be sensitive to the asymmetry in interfacial coupling between the two sublattice magnetizations and the mobile electrons, especially for antiferromagnets. We further find that the concomitant shot noise provides a useful tool for probing the quasiparticle spin and interfacial coupling.Introduction. The quest for energy efficient information technology has driven scientists to examine unconventional means of data transmission and processing. Pure spin current transport in magnetic insulators has emerged as one of the most promising candidates [1][2][3][4]. Heterostructures composed of an insulating magnet and a non-magnetic conductor (N) enable conversion of the magnonic spin current in the former to the electronic in the latter, thereby allowing for their integration with conventional electronics. In conjunction with the technological pull, these low dissipation systems have provided a fertile playground for fundamental physics [5][6][7].Commencing the exploration with ferromagnets (Fs), the focus in recent years has been shifting towards antiferromagnets (AFs) [8][9][10] due to their technological advantages [11]. While a qualitative understanding of some aspects of AFs, such as spin pumping [12,13], has been borrowed without much change from Fs, the leading order effects in several other phenomena, such as spin transfer torque [13] and magnetization dynamics [8], bear major qualitative differences. Thus, several phenomena, already known for Fs, are now being generalized for AFs [14].Although ferrimagnets (Fs) have been the subject of comparatively fewer works [7,15,16], their high potential is undoubted. The additional complexity of their magnetic structure comes hand in hand with broader possibilities and still newer phenomena. The spin Seebeck effect [17][18][19] in an F with magnetic compensation temperature has unveiled rich physics due to the interplay between the opposite spin excitations in the magnet [16]. Further studies have asserted an important role of the interfacial coupling between the magnet and the conductor [20]. While yttrium iron garnet is a ferrimagnet and has been the subject of several studies [1,3,4,[21][22][23], it is often treated as a ferromagnet on the grounds that only the low energy magnons are important [24].In this Letter, we evaluate the spin pumping current (I sz ) and the concomitant spin current shot noise [S(Ω)] in a F-N bilayer [ Fig. 1(a)], when one of the F eigenmodes is driven into a coherent sate. A two-sublattice mode...

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“…Their fast magnetization dynamics, with the potential to cover the Terahertz range [3,18], and the lack of net magnetic moment [18], have instigated a growing interest in antiferromagnets (AFMs). AFM insulators are particularly interesting due to the absence of Joule heating caused by the scattering of charge currents [21][22][23][24]. The focus is rather on the spin currents carried by magnons, the quantized excitations of the magnetization dynamics.…”

Section: Introductionmentioning

confidence: 99%

Magnon-polarons in cubic collinear antiferromagnets

et al. 2019

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We present a theoretical study of excitations formed by hybridization between magnons and phonons -magnonpolarons -in antiferromagnets. We first outline a general approach to determining which magnon and phonon modes can and cannot hybridize in a system thereby addressing the qualitative questions concerning magnonpolaron formation. As a specific and experimentally relevant case, we study Nickel Oxide quantitatively and find perfect agreement with the qualitative analysis, thereby highlighting the strength of the former. We find that there are two distinct features of antiferromagnetic magnon-polarons which differ from the ferromagnetic ones. First, hybridization between magnons and the longitudinal phonon modes is expected in many cubic antiferromagnetic structures. Second, we find that the very existence of certain hybridizations can be controlled via an external magnetic field, an effect which comes in addition to the ability to move the magnon modes relative to the phonons modes.arXiv:1812.09239v1 [cond-mat.mes-hall]

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Enhanced Spin Conductance of a Thin-Film Insulating Antiferromagnet

Cited by 52 publications

References 32 publications

Spin transport in thick insulating antiferromagnetic films

Spin transport in thick insulating antiferromagnetic films

Spin Pumping and Shot Noise in Ferrimagnets: Bridging Ferro- and Antiferromagnets

Magnon-polarons in cubic collinear antiferromagnets

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